Perimeter Calculator

3,716 calculations

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📝 How it works:
Calculate perimeter for circles, triangles, rectangles, polygons and more. With formulas and examples.

Fill in the fields below and click "Calculate".

Shape

Radius (r) (cm)

length (a) (cm)

width (b) (cm)

Side a (cm)

Side b (cm)

Side c (cm)

Perimeter Calculator - Free Online Tool

Calculate perimeter of rectangles, circles, triangles and polygons Our calculator provides fast, accurate, and free calculations for your needs.

How to Use Perimeter Calculator

Simply enter your values and get instant results. No registration required, works on all devices.

Key Features

Accurate Results: Mathematically precise calculations
Free to Use: No limits, no ads, no registration
Mobile Friendly: Works on smartphones and tablets
Instant Results: Real-time calculations

Why Use Our Perimeter Calculator?

Trusted by thousands of users daily. Fast, reliable, and always available. Perfect for professional and personal use.

Circle circumference table

Circumference C = π × d. Common diameters, rounded to one decimal place:

Diameter d	Radius r	Circumference C
5 cm	2.5 cm	15.7 cm
10 cm	5.0 cm	31.4 cm
15 cm	7.5 cm	47.1 cm
20 cm	10.0 cm	62.8 cm
25 cm	12.5 cm	78.5 cm
30 cm	15.0 cm	94.2 cm
40 cm	20.0 cm	125.7 cm
50 cm	25.0 cm	157.1 cm
60 cm	30.0 cm	188.5 cm
80 cm	40.0 cm	251.3 cm
100 cm	50.0 cm	314.2 cm
120 cm	60.0 cm	377.0 cm
150 cm	75.0 cm	471.2 cm
200 cm	100.0 cm	628.3 cm

Room perimeter (e.g. for baseboards)

For rectangular rooms: P = 2 × (length + width). Subtract door openings from the trim length.

Room size	Area	Perimeter
10 × 10 ft	100 sq ft	40 ft
10 × 12 ft	120 sq ft	44 ft
12 × 12 ft	144 sq ft	48 ft
12 × 14 ft	168 sq ft	52 ft
14 × 16 ft	224 sq ft	60 ft
16 × 20 ft	320 sq ft	72 ft
3 × 3 m	9 m²	12 m
3 × 4 m	12 m²	14 m
4 × 4 m	16 m²	16 m
4 × 5 m	20 m²	18 m
5 × 5 m	25 m²	20 m
5 × 6 m	30 m²	22 m
6 × 8 m	48 m²	28 m